andeeson



(No Model.)

G. W. ANDERSON.

GUT-OFF VALVE.

Patented Nov. 11

, llhvrrnn Smarts Parent @rrrc GEORGE XV. ANDERSON, OF VVESTPORT,INDIANA.

CU'l' OFF VALVE.

s'PEcIrIcA'rxoN forming part of Letters Patent No. 307,738, datedNovember 11, 18%.

Application filed December-'29, 1583.

T0 aZZ whom it may concern.-

Be it known that LGnonen W. ANDERSON,

of XVestport, in the county of Decatur and State of Indiana, haveinvented certain new and useful Improvements in Gut-Oil Valves; and I dohereby declare the following to be a full, clear, and exact descriptionof the inven tion, such as will enable others skilled in the art towhich it appertains to make and use the same.

My invention relates to an improvement in steam cut-0ft" valves, theobject being to provide simpleand effective mechanism by means of whichback-pressure on the exhaust side of the piston shall be prevented, nomatter at what part of the stroke the steam may be cut Off.

With this end in view myinvention consists in a slide-valve constructedin two sections, similar to the ordinary cut-ofl, firmly connected andadaptedto engage movable blocks, which blocks open and clbse theexhaustports.

My invention further. consists in certain features of construction andcombinations of parts, as will be fully described, and pointed out inthe claims.

In the accompanying drawings, Figure 1 is a longitudinal sectional Viewof the valves in position within the steam-chest when the piston isabout completing its stroke to the right; Fig. 2,the same when thepiston is about conr pleting its stroke to the left. Fig. 3 is a planview of the bottom of the valve, and Fig. 4 is a modification.

A is a steanrch est of any approved construction in connection with thecylinder B. The steam cut-off valve 0 and O is constructed to slide overthe steam-ports D and D, alternately opening and closing the same. Thetwo exhaust-portsE and E are situated under the chambers a and a in thevalve 0 and 0. Blocks of metal, Fand F, are constructed of sulficientlength to fit transversely in the chambers a and a. of the valve 0 andC, and to have an easy sliding motion therein. The thickness of theseblocks F and F is much less than the height of the chambers a and c,thus allowing the steam a free passage between the upper surfaces of theblocks and the tops of the chambers. The blocks F and F are providedwith projecting corners a with which the inner walls of the chambers aaal- (No model.)

ternately come in contact. The distances :1; and 00 between thesteanrport D and the exhaust-port E, and between the steam-port D andthe exhaustport E are equal in width to the blocks F and F, thusallowing the said blocks to rest between a steam andl exhaust port andleave both open. The shoulders or projections a on the blocks F and F,which engage the walls of the chambers a c, are of such extent that theydo not come in contact with the chamber-walls and cause the blocks F andF to move until the stroke of the piston is nearly completed in eitherdirection. Sup pose the eccentric to be so adjusted that the steam shallbe cut off at the end of one-third of the stroke. At the beginning ofthe stroke toward the right the steam-port D is open to the steam-chest,the steanrport D open to the chamber a, the exhaust-port E open,and theblock F situated on the rest between D and E. At the end of onethird ofthe stroke the port D is closed to the steam-chest by the motion of thevalve 0 G toward the left, while this motion of the valve has not yetdisturbed the blocks F and F, nor will it move these blocks until thepiston is just to complete its stroke, when the block F will slide overthe port E and the block F be removed from the port E. From the time thesteam was cut off at the end of the first third of the stroke until justas the stroke was completed the exhaust E remained open and the exhaustE closed. The expansive force of the active steam was thus exerted in aslight degree under the section 0, while no resistance took place infront of the piston by the compression of expended steam, or only somuch as might be required to lift the block F if this block has slidpartially or entirely over the steam-port D before the strokeiscompleted. At the end of the stroke, the steam-port D being new open tothe steam-chest and the port D open to the chamber a, and theexhaustport E being also open, the operation of the parts as abovedescribed will be repeated in reverse order. The pressure of the activesteam under the valve after the steam has been cut off from the chesthas a tendency to lessen the friction of the valve on its seat bypartially counterbalancing the pressure exerted by the steam in thesteam-chest.

The modification represented in Fig. 4 consists in leading thesteamports from the ends of ,the cylinder towarcfthe middle of thesteamchest, placing the exhaust ports near each other, and constructingthe sections of the valve 0 and O integral. The operation is in everyrespect the same as described. The blocks F and F are held in positionover the exhaust ports by the pressure of the steam, and are preventedpitching too far by means of rollers z, mounted in spring-straps z,whichhold the rollers against the upper surfaces of the chambers with lightpressure. This latter device is desirable when the engine is to bedriven at a high rate of speed, and the blocks thereby rendered moreliable to move farther than is necessary.

Having fully described my invention, what I claim as new, and desire tosecure by Letters Patent, is

1. The combination, with a cylinder having a steam-port and anexhaust-port, of a sliding ports and a steam-chest, of a sliding cut-offvalve having two separate compartments firm; ly connected, and themovable blocks within these compartments, the said blocks being moved bythe valve so as to alternately close and open its respectiveexhaust-port atthe proper moment, substantially as set forth.

3. The combination, with a cylinder provided with ports and asteam-chest,of a sliding valve provided with compartments,and movablesections whichare provided with projecting corners and constructed toslide within these compartments,thereby opening and closing theexhaust-ports, substantially as set forth.

4. A sliding cut-01f valve consisting of the sections 0 0, provided withthe chambers to a, the movable blocks F and F, and the bearings z,constructed and arranged substantially as set forth.

In testimony whereof I have signed this specification in the presence oftwo subscribing witnesses.

GEORGE W. ANDERSON.

Witnesses:

MILTON M. MEWHINNEY, J AS. T. OONNELL.

